Table fields from other tables Also called Non-Base Table Fields.

1. Table fields from other tables Also called Non-Base Table Fields. In the example of CUSTOMER, the Sales Area is known by number, but not the description of the Sales Area. This has to be obtained from another table, SALESAREA. A trigger needs to be created that will insert the sales area description when the sales area number appears.

2. Adding a new field from another table to an existing data block i.e. AreaName from SALESAREA to the CUSTOMER data block Highlight CUSTOMER. Right-click and invoke the Layout Editor

3. The description needs to be added here. Click on the Text Item tool. This will create a new field in the data block

4. A new item, TEXT_ITEM6 has been added. The same height and y-coordinates as Sales Area can be obtained by using the property palette.

5. In the Property Palette, change the name to DESCRIPTION.

6. The name has been changed to DESCRIPTION.

7. In the Property Palette, make the following changes. Enabled: Yes Keyboard Navigable: No – prevents the users tabbing into this field Database Item: No – i.e. does not map to an attribute in the CUSTOMER table Query Only: No Primary Key: No Insert Allowed: No Query Allowed: No Update Allowed: No Prevents any of the actions from happening

8. Notice some of the changes made here for the DESCRIPTION field The new data item, DESCRIPTION, has now been added to the data block. But it is not yet known where to get the data to fill this field. This is done by creating a trigger.

9. Creating a trigger for the DESCRIPTION field There are different types of triggers upon the execution of an event: 1. PRE – the trigger fires before the event. 2. POST – the trigger fires after the event. 3. WHEN – the trigger fires in place of the event execution. 4. KEY – the trigger fires when a certain key is pressed. In this example the trigger will fire after the Sales Area field changes in the CUSTOMER data block. This requires that a POST-CHANGE trigger is created on the :CUSTOMER.CompanySalesArea field. This is performed by first opening the Object Navigator The colon indicates that it comes from a data block

10. Within the CUSTOMER data block, highlight COMPANYSALESAREA, and then click on Triggers

11. The following pop-up appears. Scroll down to POST_CHANGE

12. POST_CHANGE has been selected Click OK

13. The PL/SQL Editor. The code for the trigger is now entered. A POST_CHANGE The CUSTOMER data block and the COMPANYSALESAREA field

14. Once the code is entered, compile the PL/SQL code Enter the following code This shows that the PL/SQL has not yet been compiled. The code is being modified

15. Once compiled, EXIT The code is not being modified The code has been compiled

16. There now is a POST_CHANGE trigger for COMPANYSALESAREA

17. Compile and run the CUSTOMER form

18. The Sales Area description now appears. Try modifying or deleting the field. It should not be allowed if the previous steps were performed correctly

19. A new LOV can now be created when the Customer Detail frame is displayed. The previous LOV just displayed different sales areas by number. The new LOV should also show Area Name. LOV shown from previous slide show. This LOV should be deleted to be replaced by the new LOV Highlight both of these items and then delete them by: Edit, Clear.

20. Highlight LOV under CUSTOMER and pull down the Edit menu and enter Create

21. Choose the LOV Wizard

22. Enter this SQL statement. Notice that this is a join because items from two tables are needed. Click Next

23. Include both CompanySalesArea and AreaName

24. Change the names as shown Choose Automatically size columns and click Look up return item

25. Each return value has to be looked up separately. The return value for Number is Customer.CompanySalesArea. The return value for Name is Customer.Description Click Next

26. Enter the name as shown

27. Retrieve 6 records

28. Both return items are assigned to the LOV

30. The LOV is created Compile and run the form

31. The LOV showing the six sales areas